AMBER/VLTI observations of five giant stars

Autor(en)

Felice Cusano, Claudia Paladini, Andrea Richichi, Eike W. Guenther, Bernhard Aringer, Katia Biazzo, R Molinaro, Luca Pasquini, Artie P. Hatzes

Abstrakt

While the search for exoplanets around main sequence stars more massive than the Sun have found relatively few such

objects, surveys performed around giant stars have led to the discovery of more than 30 new exoplanets. The interest in studying

planet hosting giant stars resides in the possibility of investigating planet formation around stars more massive than the Sun. Masses

of isolated giant stars up to now were only estimated from evolutionary tracks, which led to different results depending on the physics

considered. To calibrate the theory, it is therefore important to measure a large number of giant star diameters and masses as much as

possible independent of physical models.

Aims. We aim in the determination of diameters and effective temperatures of 5 giant stars, one of which is known to host a planet.

We used optical long baseline interferometry with the aim of testing and constraining the theoretical models of giant stars. Future

time-series spectroscopic observations of the same stars will allow the determination of masses by combining the asterosimological

analysis and the interferometric diameter.

Methods. AMBER/VLTI observations with the ATs were executed in low resolution mode on 5 giant stars. In order to measure high

accurate calibrated squared visibilities, a calibrator-star-calibrator observational sequence was performed.

Results. We measured the uniform disk and limb-darkened angular diameters of 4 giant stars. The effective temperatures were also

derived by combining the bolometric luminosities and the interferometric diameters. Lower effective temperatures were found when

compared to spectroscopic measurements. The giant star HD12438 was found to have an unknown companion star at an angular

separation of ~ 12 mas. Radial velocity measurements present in the literature confirm the presence of a companion with a very long

orbital period (P ~ 11.4 years).

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

INAF-Osservatorio Astronomico di Bologna, National Astronomical Research Institute of Thailand (NARIT), Thüringer Landessternwarte Tautenburg, INAF - Osservatorio Astronomico di Padova, INAF-Osservatorio Astronomico di Capodimonte, European Southern Observatory (Germany)

Journal

Astronomy & Astrophysics

Band

539

Anzahl der Seiten

7

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201116731

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/f567a7d8-4786-4de8-a1ed-a9f03fa1cb02